Adjustable and movable sundial



y 5, 1953 E. A. VIESTURS 2,637,108

ADJUSTABLE AND MOVABLE SIINDIAL Filed May 31, 1950 INVENTOR 54,4: A- Via/v4 BY/4M/ 70% ATTO RN EY Patented May 5, 1.953

AnpIicatiQnMay 1, 1950, Serial. No.1 1.653205? In Germany ober 1., 1%8.

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1 Claim.

My invention relates to an adjustable sundial, and more particularly to a sundial which may be moved from one place to another.

The new sundial according to my invention is especially adapted to be carried around.

The usual generally known sundials are sta-- tionary. They consist of a plate with the time scale and a fixed pointer connected with the plate, the shadow of which falls on the time scale of that plate. In the course of a day, the tip of the shadow describes a curve on the plate which has a greater or lesser circumference depending on the seasonable sun's altitude. In consequence, the graduation of hours on the time scale is not uniform, which disturbs the reading. The plate or time scale of these known sundials must be adjusted once in the north-south direction at its installation.

This invention relates to a movable sundial readable everywhere, for instance a portable sundial for use as a Watch or a wrist-watch. Portable Sundials of this kind are intended mainly for play and sport, where a good mechanical watch is endangered by pressure, sand, and water, and therefore not always adapted to be carried around. As play and sport are mostly exercised during sunny weather, a portable sundial can well replace a mechanical watch on these occasions.

According to the invention my new sundial comprises a time scale and a shadow-pointer both revolvable around a common axis, said axis to be held in vertical position during the reading of the dial. A magnetic needle is provided in order to bring the time scale in the north direction before each reading.

In order to allow general use of the sundial according to the invention means are provided for eliminating the difference between the actual meridian of the place of reading and the meridian of the corresponding standard time. purpose, the plane of the shadow-indicator can be turned in a horizontal direction with respect to the bottom of the upper part or to the time scale, e. g. by a turnable ring carrying the pointerthreads, and the parts adjustable against each other may be provided with corresponding marks, e. g., the bottom having marks for the geographic meridians and the ring having marks for the meridians of special standard times.

An embodiment of the invention is to be described in the following, by way of example, with reference to the accompanying drawing.

The portable sundial of the invention comprises a casing a. If the dial is formed as a wrist-watch, this casing 11. has bails al for the fastening of the watch-band.

For that Mounted within casme: a; is a treelytwritable. magnetic, needle I) carrying a ring 0 on which the time scale is attached; The casing a has a turnable upper part (1 with a glass disc e and a bottom h.

In addition, the turnable upper part cZ comprises a turnable ring Z carrying the shadow indicator. In the embodiment as shown, the shadowindicator is formed by two threads 1, one above the other, and stretched by small springs. With parts id and Z in the proper relation, the time can be read through an opening 9 if the shadows of both these threads coincide on the bottom h of the uppper part d.

The arrangement of ring Z in the upper part d permits shifting of the shadow-indicator f with respect to the reading-aperture g. The difiererence between the actual meridian of the place of the reading and the meridian of the corresponding standard time can be corrected for before reading thetime by shifting the shadowindicator. In order to simplify this correction, the ring Z carries on the inner side marks m of dillerent standard times, e. g. E. S. T., C. S. T., M. S. T., P. S. T., etc. Furthermore, on the bottom it of part (1 the geographic meridians are marked in such a manner that any mark 111. of the ring Z can be adjusted selectively on the meridian corresponding to the place of reading.

As long as the user of the sundial is staying in the proximity of the local meridian the correcting ring Z is to be adjusted only once. The adjustment has to be changed only if the user essentially moves away from that meridian.

The sundial as illustrated can be used in wide areas, e. g. all of North America, etc., or also over the whole world without any difiiculties depending on the number and the kind of the marks.

The rather extensive pendulation of the magnetic needle I) and of ring 0 may delay or disturb the reading. Consequently, it is advisable to make the casing a liquid-tight and to fill it with a liquid, as e. g. alcohol, which dampens the pendulation of the magnetic needle and ring. In this form, the bottom 71. is made of transparent material or at least provided with a transparent section in place or the aperture g in order that ring 0 is well visible.

The invention is not restricted to the embodiments as shown and described but relates to all changes of form which are possible or desirable within the scope of the invention as defined by the claim.

What I claim is:

An adjustable sundial comprising a casing, a

turnable upper part on said casing and a bottom on said upper part, a transparent cover supported by said upper part for rotation relative thereto, a magnetic needle pivoted centrally in said casing, a ring having a time scale marked thereon disposed on said magnetic needle, said bottom having an opening and an index thereat for permitting the reading of the time on said time scale ring, a shadow indicator fixed on said turnable cover on top of th casing, said shadow indicator consisting of to elongate thread-like elements the shadows of which should coincide when the time is read through said opening, means for correcting for the difference between the geographical meridian of the place of reading and the meridian of the corresponding time, including standard and daylight saving times, which means of correction comprises marks on the bottom of the upper casing part for the geographical meridian, and on the cover for the meridian of the special time.

ERICHS A. VIESTURS.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Smith Aug. 23, 1870 Benson Mar. 8, 1887 Kittelson Oct. 24, 1950 FOREIGN PATENTS Country Date Great Britain May 11, 1880 Great Britain Feb. 8, 1896 Great Britain Dec. 2, 1893 Denmark Mar. 15, 1943 Denmark Oct. 22, 1945 France Mar. 3, 1875 Germany May 3, 1924 

